Image source, Getty Images

Murray looks a little shell-shocked as he throws up for the second game. As does coach Amelie Mauresmo, who grimaces up in the Briton's box.

Dimitrov hammers a backhand return on Murray's second serve to go 30-30, then the pair trade points as we go to deuce. Murray goes to the review system to claim back a wrongly-called serve and another rasping opener can only be palmed into net by Dimitrov.

Murray on the scoreboard.

Pat Cash,, external 1987 Wimbledon champion: "#andyMurray or #dimitrov?? Having watched Dimitrov closely last match, not sure he has enough to hurt Murray on a cool night, we will see."

Dimitrov is pumped! The Bulgarian lets out a whoop as Murray goes long again for 30-30 after the pair exchange punch and counter punch in a rally. No way back for the Briton, who slaps a big Dimitrov serve into the net.

Murray's service game has been the cornerstone of his Australian Open campaign thus far. But it has already been smashed apart.

Dimitrov takes the first point with a sumptuous forehand that licks the paint before moving the gears to earn two break points.

He needs just one. Murray's return goes big, he challenges the call, he's wrong. Perfect start for Dimitrov.

Former Australian Open winner Victoria Azarenka:, external Feels like I need some popcorn for tonight to watch Andy Murray vs Grigor Dimitrov #shouldBeReallyInteresting Who's watching?

Piers Newbery
BBC Sport at Melbourne Park

"You might not believe me if you're in or near the UK, but it's a bit chilly in Melbourne this evening. Last year's 40C days are a distant memory and we're down to a breezy 18C on Rod Laver Arena this evening. A few squeals in the crowd signalled the arrival of Dimitrov and a significantly throatier roar greeted Murray."

Grigor Dimitrov means business judging by the opening game.

The Bulgarian is aggressive from the first toss, thundering down big serves and hammering the passing forehands. Murray has little answer and it is a comfortable hold.

Goran Ivanisevic
2001 Wimbledon champion on BBC Radio 5 live sports extra

"Andy is my favourite to make the final. I feel he is ready to be there and maybe win, he is ready to win more Grand Slams.

"It wasn't Andy at Wimbledon last year. It was some other Andy. I don't know how he even got to the quarter-finals. This is completely different - he's really focused."

Here we go. Dimitrov to keep off the action....

BBC Radio 5 live sports extra

Gigi Salmon and the BBC 5 live sports extra team have cranked up the generator and are broadcasting loud and clear from Melbourne Park.

Former Wimbledon champion Goran Ivanisevic is providing expert analysis - to the relief of the 5 live sports extra team. The Croatian decided to play a practical joke on them by claiming he had forgot about the job. He was sat in the restaurant waiting for them...

You can tune in on your digital radio, but, if all that seem like too much hassle, then just click on the play button at the top of this page. Don't forget to keep reading though.

Never forget that...

It is chilly in Blighty. And it is hardly balmy as night falls in Melbourne. Let's warm things up by generating some social media heat.

Earlier we talked about Andy Murray's bad day at the office at the hands of Dimitrov at Wimbledon. So why don't you tell me about your own bad days at the office (sporting or actually at your place of employment)? In fact I insist.

Use #bbctennis on Twitter, external or text 81111 if that's more your thing.

The countdown is ticking down quickly. Both players march out on to court in the Rod Laver Arena to a generous round of applause from the packed stands. If sporting fashion is something you are particularly interested in, you'll be keen to know Andy Murray is decked out all in black. Like a slimmer, less scary Jonah Lomu....

Image source, Getty Images

Now Murray has the chance to gain his revenge against Grigor Dimitrov, the Bulgarian who ripped his Wimbledon title out of his grasp and trampled all over it in straight sets on Centre Court.

Dimitrov, aka Mr Maria Sharapova,, external stands between Murray and a place in his 16th straight Grand Slam quarter-final.

Revenge is best served cold so they say. Ice cold, lukewarm, boiling hot - whatever the temperature - Murray will enjoy it.

We've all had bad days at the office. Because we've not met the strict deadline for that important piece of paperwork. Because we've had a schooling by some smarmy colleague in a meeting. Because we've had a blazing row with the gaffer.

But the difference between the likes of us and Andy Murray (unless you're a professional sportsman too) is that those bad days are not played out in front of the eyes of millions around the world.

Unfortunately, the British number one had one of those days back in July. At Wimbledon. As he defended his men's singles crown in SW19.

Image source, Getty Images

"Today was a bad day. I made many mistakes, unforced errors, and then started going for too much and taking chances that weren't really there.

"I think I hit maybe one backhand winner the entire match, which isn't normally what I do. It was a tough day all around."

Andy Murray. Wimbledon. July 2014.